Trail Speak

Through the trails, the mountain passes and the left-over road signs along the massive highways and streets; there are markers displaying a variety of signals for travelers far and wide to keep them safe and make sure everyone is aware of where they're going. Adapted from the times of old from a mixture of hiking signs used by experienced teams of search and rescue as well as the signs from vagrants that helped shape the new communities that grew into settlements of today.
As you pass over a bridge you'll come across a wooden sign, etched into it with all the knowledge you'd need to know for the next few miles as you go. You can touch it, or look into the etched wood that's been filled in with dirt and clay to see the symbols.
FOOD NEXT MILE. HOLD TONGUE. So you know there might be people there, and as long as you're holding your tongue, being kind, you'll be able to get yourself something to eat along the way.
Now that you've made it out of the woods, up through the valley and you're headed towards the mountain you might find similar signs painted on the old markers left on the side of the cracked road. The people in town told you that there's been a few gangs of bandits that have been wreaking havoc, and you took a job to help clear them out in exchange for food and some books along the way.
CAMP OCCUPIED. BAD NEWS. At least you know you're close.
The signs along the way may take on a few varied shapes and perhaps a different orientation, but the messages are often clear enough. You don't need words to read them, and the placements are set in stone through all the times you've seen them in your youth, with your family and friends as you've moved from town to city to settlement and each place you've stayed in. These symbols hold a language for you. It is a language built on symbols for travelers alone and ones who do not hold the knowledge of the world around them.